Support structure for a wind turbine

Abstract

The invention relates to a modular, X-shaped support structure for accommodating multiple wind turbines. Two intersecting rotor support arms, each with at least one rotor at one end, are pivotally mounted at their intersection via a horizontal swivel joint. The axis of rotation is held by a separate support structure, which is rigidly connected to a rotatable base structure. An elastic connection system is arranged between the free ends of each rotor support arm and the base structure. This system allows for fine adjustment of the rotor positions relative to each other, exhibits elastic properties for vibration damping, and can be released to enable a pivoting action, allowing the rotor support arms to be lowered by winches. The modular support structure allows for various geometries and materials and is particularly suitable for small to medium-sized systems, including mounting on buildings or containers.The invention improves the economic efficiency, ease of maintenance and structural decoupling of the wind turbine.

Description

[0001] The invention relates to a modular support structure for accommodating multiple rotors for converting wind energy, e.g., into electrical energy. State of the art

[0002] Conventional wind turbines typically use a single large rotor with a horizontal axis of rotation, mounted on a rigid tower. Wind direction tracking is achieved via a slewing ring at the tower head. To utilize higher wind speeds at greater heights, tall tower designs are implemented. However, with increasing tower height, the structural requirements for the tower base, foundation, and tower wall thickness increase disproportionately, leading to significantly higher costs and increased material usage. Furthermore, vibrations and resonance effects between the rotor and tower become more pronounced, limiting the turbine's lifespan.

[0003] To mitigate these problems, multi-rotor concepts are being investigated, in which several smaller rotors are arranged on an extended support structure. This allows the rotor area to be distributed across different subunits, resulting in less stress on individual components. The overall power output of the multi-rotor wind turbine can be varied by the number of identical rotors. The high number of identical components reduces investment and operating costs. Prototypes and studies already realized, for example by Vestas, Aerodyn, and Mingyang, demonstrate the fundamental feasibility of multi-rotor wind turbines, but their support structures are strongly based on conventional tower structures with their associated characteristics, leading, for example, to high installation and operating costs.

[0004] Document GB2443886 discloses a multi-rotor wind turbine in which the rotors are attached to a pivotable crossbeam which can be rotated in an essentially vertical plane to bring one of the two rotor / nabulb units close to the base of the tower.

[0005] From publication EP0761964A1, a wind turbine with two rotors supported by arms in a V-arrangement is known. The arms are hinged to a base that pivots around a vertical column on rollers. The arms are normally held in the V-position by a tie rod and a strut, but can be lowered for rotor maintenance.

[0006] Methods to positively influence system vibrations in the direction of the rotor rotation axes (fore-aft vibrations) or torsional vibrations by targeted control of the blade adjustment of the individual rotors are known from publications US11994108B2, WO2019042515A1 and US7692322. Object of the invention

[0007] The technical problem underlying the invention is to provide a support structure for a multi-rotor wind turbine that offers increased economic efficiency, reduced structural requirements, improved maintainability, and higher operational reliability compared to conventional single-rotor turbines. In particular, the novel support structure is intended to enable effective force distribution, targeted vibration damping, and a simple way to lower the rotors for maintenance or in extreme weather conditions. At the same time, it should allow the system to be adapted to different installation locations, especially on existing infrastructure such as building roofs or containers. Solution to the task

[0008] The invention discloses a wind turbine with a segmented, X-shaped support structure comprising two rotor support arms, each with at least one rotor at one end, which intersect at a common pivot point. A pivot joint is arranged at this intersection point, allowing the arms to pivot about a horizontal axis. The axis of rotation is held by a support structure rigidly connected to the rotatable base structure.

[0009] An elastic connection system is provided between the free ends of the rotor support arms and the base structure, performing several functions: fine-tuning the rotor positions relative to each other, elastic damping of operational vibrations, and controllable disconnection of the connection to enable the lowering process. The lowering process is achieved by controlled pivoting of the rotor support arms around the horizontal axis of rotation, with one or more winches used for controlled holding and lifting.

[0010] The modular design of the support structure allows for different geometries and material configurations, adapted to the rotors used and the specific site conditions. This enables the system to be implemented in a material-efficient, easy-to-assemble, and dynamically stable manner. The invention is particularly suitable for small to medium-sized wind turbines, which can also be mounted on existing structures such as building or container roofs.

[0011] The invention is described in more detail below with reference to exemplary embodiments in conjunction with the drawing. The drawing shows: Figure 1 shows a side view of the wind turbine with an x-shaped support structure and a central swivel joint. Figure 2 This is a schematic representation of the fine adjustment of the rotor spacing by the elastic connection system. Figure 3 illustrates the pivoting process of the rotor support arms during lowering. Figure 4shows a variant with external rotor support arms for the support structure. Figure 5 illustrates a central support structure for the bearing of the pivot axis. Figure 6 shows an interlocking structure for shrouded rotors as well as the setup on a container roof. Figure 7 This represents a multiple configuration of the support arms with several horizontal axis rotors. Figures 8 and 9 show variants with vertical axis rotors. Description

[0012] According to the invention, this problem is solved by a modular support structure for multi-rotor wind turbines as defined in the attached claims. The solutions described below are particularly suitable for small to medium-sized wind turbines, for example, with a total rated output of less than 200 kW and / or a tower height of less than 50 meters. For larger turbines, the mechanical stress and the complexity of the slewing and damping mechanisms may technically limit feasibility. Turbines of the intended size can, for example, also be erected and operated on existing buildings or other structures, such as containers.

[0013] According to the invention, the modular support structure carries at least two identical rotors (the term rotor here refers to the system comprising the components of a wind turbine required for converting wind energy, e.g., into electrical energy, and typically arranged on the tower, e.g., rotor blades, gearbox, generator, nacelle, etc.). These can be equipped with a horizontal or vertical axis of rotation. In the case of rotors with a horizontal axis, these are aligned approximately parallel to each other.

[0014] The rotors (1) and (3) are attached to the ends of two equally long, intersecting rotor support arms (2) and (4), which together form an X-shaped arrangement. These rotor support arms are mounted at their intersection via a pivot joint (5), which allows the rotor support arms, with the rotors at its ends, to pivot about a substantially horizontal axis and to make slight tilting movements perpendicular to the plane of rotation. The axis of rotation is supported by a separate support structure (8), which is rigidly connected to a base structure (6), which in turn is connected to the rotatable part of a rotary joint (7) for wind direction tracking. Figure 1 ).

[0015] The elements (2), (4) and (8) of the supporting structure ( Figure 1These structures preferably consist of several rod-shaped components that connect to form an X-shaped frame. The position of the rotor support arms relative to the support structure can vary (support arms inside or outside the support structure). They can be designed as a lattice structure, a welded tube structure, individual support columns with stiffening elements, or as composite beams with a variable cross-section along the longitudinal axis, or as combinations thereof. Suitable materials include, for example, steel, aluminum, or fiber-reinforced composites.

[0016] According to the invention, an elastic connection system (9) is provided between the free ends of the rotor support arms (2, 4) and the base structure (6), integrating several technical functions in a single component or functionally coupled assembly. This connection system fulfills the following functions: 1. Fine positioning of the rotor support arms

[0017] The connecting element enables precise adjustment of the inclination of the rotor support arms and thus of the distance between the rotor surfaces, in particular to adjust a desired aerodynamic interaction of the flow through the rotors, which leads to an increase in performance. (Figure 2)

[0018] Possible implementation options: Spindle mechanism with lock nut, eccentric adjustment with locking mechanism, hydraulically or pneumatically controlled pressure chamber, actuator with threaded drive 2. Adjustable elastic properties for vibration damping

[0019] The connection system possesses elastic properties to selectively dampen operational vibrations (e.g., rotor resonances, tower movements) and prevent structural damage. The stiffness can be constant or adjustable.

[0020] Possible implementation options: Coil spring (linear or progressive) Elastomer element with defined modulus Combined spring-damper system (e.g., hydraulic) Piezoactive or magnetorheological damping (adjustable) Preloaded friction system for energy dissipation 3. Controlled release of the connection to enable swivel movement

[0021] The elastic connection system can be released actively or passively to allow the rotor support arms to lower by pivoting.

[0022] Possible implementation options: Mechanical locking system with release bolt (remotely controlled or electrically operated) Electromagnetically actuated coupling unit Pneumatically or hydraulically unlockable block mechanism Thermally activated shape memory elements (for overload cases)

[0023] The rotors can be lowered in a controlled manner on the rotor support arms via a winch (11) attached to the base structure, preferably a fixed winch, the ends of which are connected to the free ends of the rotor support arms. After maintenance or protective measures have been completed, the rotors can be raised again and locked in place by the connection system (9). The lowering and raising process preferably occurs synchronously to minimize any tilting moments on the support structure and the rotary bearing during these operations. This is ensured, for example, by selecting a winch with double cable winding.By means of an inventive design of the geometry for the spreading of the X-shape (formed from the angles of the rotor support arms to the vertical), the height of the intersection point (axis of rotation) above the base structure, and the position of the center of gravity of rotor support arm and rotor above the axis of rotation, when the connection at the base of the rotor support arm is released, an independent rotational movement of the rotor support arm occurs, so that the rotor is lowered towards the ground at the end of the support arm (. Figure 3Therefore, only a small amount of energy is required for the lowering process: to release the locking mechanism on the rotor support element, to control the lowering speed using a brake on the winch, and to stop the lowering process using the winch's braking function when a final position is reached. By maintaining the necessary energy reserves, a lowering process can also be triggered automatically or remotely in an emergency situation (e.g., extreme wind events combined with a power outage).

[0024] The design of the central rotary bearing (7) for tracking the wind direction of the entire system below the base structure can vary depending on the size of the system: For small to medium-sized wind turbines (preferably < 20 kW), it can be used as a compact slewing ball bearing, as a multi-row deep groove ball bearing (as in Figure 1(indicated), these can be implemented. They can transfer forces and moments from the rotating part to the stationary ground with low friction. For larger wind turbines, a segmented rail and roller construction (not shown) is advantageous, in which the support elements are guided on rollers along an annular rail element. The rollers are arranged so that the loads and moments from the operation of the system can be safely transferred to the ground via the rail, preventing the system from lifting off the rail and simultaneously enabling low-friction rotation around the vertical axis.

[0025] The rotational movement for wind direction tracking is achieved by motors via a positive or force-fit connection to the rotatable part of the rotary bearing.

[0026] Figures 4-9 show variations of the articulated support structure in conjunction with different rotors. The arrangement of the rotor support arms relative to the support elements of the axis of rotation can vary. These can be arranged internally between the support elements for the axis of rotation ( Figure 1 ) or outside ( Figure 4 ). The task of supporting the axis of rotation can also be accomplished via a centrally arranged support structure ( Figure 5 ). In Figure 6One variant is shown in which the rotor support arms and the support elements of the axis of rotation interlock. The illustration also shows the use of shrouded turbines and the mounting of the entire system on a container roof. The distribution of the operational loads across the broad base of the open support structure facilitates mounting on roofs or, as shown in the illustration, on a container roof. Ballasting the container allows for the simple creation of a heavy-duty foundation for the system.

[0027] With appropriate dimensioning, several identical rotors can be mounted on the rotor support arms. This is shown in the Figure 7 in the case of 2 horizontal axis rotors per support arm and in Figure 8 and 9 show variants that use vertical axis rotors.

[0028] The present invention has been described in more detail with reference to exemplary embodiments and modifications, as illustrated in the figures. A common feature in all embodiments is that the rotor support arms are pivotably arranged in an X-shape on a pivot axis, and this pivot axis, which need not be positioned centrally within the rotor support arms, is supported by additional support elements. The aim is always to geometrically transfer the loads from the operation of the system to the ground via a wide base. In conjunction with the positive influence of the use of the invention, particularly active elastic elements, on stable dynamic system behavior, the resulting support structure can be designed to be lightweight and material-efficient, and therefore more cost-effective compared to conventional designs.It is self-evident to those skilled in the art in this field that the embodiment of the present invention according to the illustrations described above, the reference numerals used for the respective parts and components in the illustrations and the description, and the exemplary specifications are not to be interpreted restrictively. The invention is not limited to the representations shown in the illustrations and, in particular, not to dimensions and arrangements. All embodiments and variants that fall under the attached claims are considered to belong to the invention.

Claims

1. Wind turbine with a support structure on which at least two rotor support arms are pivotably mounted about a substantially horizontal axis, wherein: the support structure is x-shaped and consists of two intersecting rotor support arm elements to which the rotors are attached at their respective ends, the rotor support arms are connected at their intersection point by a horizontal swivel joint, the axis of rotation of the swivel joint is held by a support structure which is rigidly connected to a rotatable base structure, and an elastic connection system is arranged between the booms of the rotor support arms and the base structure, which: (a) allows the fine adjustment of the rotor positions relative to each other, (b) has elastic properties for vibration damping, (c) enables controlled separation to release the swivel movement.

2. Wind turbine according to claim 1, characterized by thatThe supporting structure of the pivot axis is designed as a welded tubular frame, lattice girder or individually supported column structure with stiffeners.

3. Wind turbine according to one of the preceding claims, characterized by that The elastic connection system consists of a combination of a mechanical adjustment unit, an elastic damping element and a remotely triggered locking system.

4. Wind turbine according to claim 3, characterized by that The elastic properties of the connection system can be actively controlled.

5. Wind turbine according to claim 3, characterized by that The connection is separated via an electrically, hydraulically or pneumatically actuated locking system.

6. Wind turbine according to one of the preceding claims, characterized by thatThe geometric design of the rotor support arms and the position of the axis of rotation are such that the rotors with the rotor support arms automatically lower as soon as the locking systems are opened.

7. Wind turbine according to one of the preceding claims, characterized by that The elastic connection system can be actively released by a control command of the system control to enable the independent lowering of the support arms by pivoting.

8. Wind turbine according to one of the preceding claims, characterized by that at least one winch is provided on the base structure, the cables of which are attached to the free ends of the booms and which supports the controlled, synchronous lowering of the rotor support arms and raises the rotor support arms synchronously.

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